Apparatus for indicia recognition



N 1952 v. K. ZWORYKIN" ET AL 2,616,983

APPARATUS FOR INDICIA RECOGNITION Filed Jan. '5, 1949 3 Sheets-Sheet 2 Nov. 4, 1952 Filed Jan. 5, 1949 V- K. ZWORYKIN ET AL APPARATUS FOR INDICIA RECOGNITION 5 Sheets-Sheet 3 ATTORNEY Patented Nov. 4, 1952 7 2,616,983 APPARATUS. FOR-- mmcm RECOGNITION Vladimir K. Zworykin and Leslie E. Flory, Prince 7 ton, N; J assignors to Radio- Corporation of America, a corporation ofDelaware Application January 3, 1949, .Seri'alNo. 68,887.

I. This invention relates. to improvementsin the art of indicia recognition, and more particularly to an improved method of an apparatus. for generating electricalvoltagesor voltage groups having. a predetermined relation tolindicia of! any characteristic shape or contour outlined on a contrasting surfacel 7 While not limitedthereto, the invention finds special, application inireadin'g aids for. the. blind, and will.be particularly described in connection with. apparatus for translating indicia into acoustical energy in the form. of. sounds characteristic ofv a spokenlanguage. Forthe purpose of. simple disclosure, thedescriptionwill be limited to apparatus forrecognizing and translating indicia in the form of printed letters,.although it shouldbe understoodthat the principles of the. invention are equally applicable to the recognition and translation of. indicia which arev outlined by. perforations, stampings,

or any tracing inor on a surface whereby said indicia appear in contrast to said surface.

The prior art. relating. to. reading aids. for the blind is largely directedtomethods of'and .devices for translating printed matter into arbitrary tones or tonalcomhinations. having no relation to the soundsmormally ass'ociatedwith spoken language. (See e..-v g. U. S'.. Patents 2,420,716; 1,350,954; 2,451,014); Some. success has been achievedwith devices. of. this. type,

. but their obviouslimitation resides in. the. fact such as aspecially prepared tape havi'ngf indicia of; different lengths printed, thereon. Such an arrangement. is described in. the E copending ap: ,plication of L.v E. Flory, SerialNoU 713,175, filed November 29, 19.46. .While this arrangement overcomesthe objection to the tonal. system, it: does not provide, for. direct 1 translation. of ordinary printed matter into intelligible speech.

, -While the. principles of the. present invention are applicable to a system of the'foregoing. type, insofar as recognition of arbitrarily shaped or coded indicia is concernedit .willbecome apparent as the-following.-description proceeds that thetinvention is not limited to .the recognition of coded indicia, but. is equally applicable to..recognition and translation .of ,.intelligible indicia It is, accordingly, a principle object of the 113,-

Glaims; (Cl. 179100.3)

vention. to provide; an improved method of; and apparatus for recognizing indicia outlined. on a contrasting surface,. andfor translating recognized indicia into usable form;

' A further object of the. invention is to provide an improved method and apparatus for translatingprinted matter into intelligible sounds.

Another object of the invention is to provide an improved method and I apparatus for controlling the operationof a. soundreproducer.

A further. object of the invention is the provision of an improved device for translating changes in reflected light" energy from printed matter. into .useable voltagesor'voltage groups.

Another. object of the invention is to provide a device for audibly. reproducing; the individual letters and other elemental-characters of printed material.

According to the inventionrthe foregoing and other objects and advantages .areattained by scanning an.indicia-bear ingsurface with a plurality of. lightbeams which serve to divide the scanned. surface into segmental zones. be brought out. more fully hereinafter, an. indicia-bearing. surface scanned. in. the foregoing mannerfexhibits a distinctive pattern of light reflecting properties. The invention provides for recognition-of, each such distinctivepattern by counting the. number of changes in light reflection occurring in each of the zones, and for controlled reproduction of' the particular speech sound. corresponding. to the indicia recognized. j I v i A. more complete; understanding of the invention may be 'had'by TBfCIGIICG'tO the follow- Figure. 21s. a.view, partlyf inperspective and partly .in..block.diagram ,iorm, showing .a complete reading aidapparatus arranged. in accordance with'the invention; 4 A e Figure. 3. is. a view onthe line; 3"3' of Figure 4,

. and shows alight projection j system'suitable-for and lightipickiipud usein thereadinglaid'of FigurefZ; 'j

e .vlew one; light" projection ce suitable for use asascanner'in the system Figure'ZL Q v Eigure. a. s.ecft 1lon. View on the line-5: 5 of Figure. .4 is, .a .sid

F gure 4;

As will.

Figures 6, 7 and 8 are schematic diagrams of electrical circuits corresponding to the lettered blocksof Figure 2, and

Figure 9 is a side view of a modified form of scanner for use in the apparatus of Figure 2.

One of the general principles on which the present invention is based can best be explained by reference to Figure 1, wherein there are shown four arbitrarily selected letters, 0, b, w, p, such as might be found in an ordinary line of printed matter. In Figure 1, the letters are to be scanned by five spots of light S1-S5 originating in five light beams (not shown). The spots of light S1S5 may be said to divide the line of printed matter into five segmental zones Z1Z5 defined by the paths of the light spots (or beams). The number of zones used is not critical, provided a sufficient number is used to distinguish between the letters. A five-zone system has been selected as illustrative of the invention, and it is believed that a minimum of five zones should be used to avoid having ambiguous results.

When the spots of light S1--S5 in Figure 1 are moved from left to right across the printed letters o, b, w, p, the amount of light reflected from each of the zones Z1-Z5 will vary as each of the light spots encounters the contrasting black and white areas defined by the portions of each letter-outline appearing in each zone. This is illustrated by the five lines L1-L5 which have been placed beneath the letters in Figure l, and which represent the reflecting properties of the printed matter within each of the five zones Z1-Z5. shaded, offset portions of the lines L1L5 correspond to subnormal or black reflecting portions of the printed matter, while the unshaded portions of the lines L1L5 represent contrasting normal or white reflecting portions of the printed matter in Figure 1.

It will be noted that each of the letters in Figure 1 exhibits a characteristic light reflection pattern as the letters are scanned by the light spots S1S5. This is illustrated by. the table shown in Figure 1a, wherein the number of reflection changes per letter per zone is tabulated. It can be seen in Figure 1a that there is a unique combination of reflection changes per letter per zone for each of the four letters shown. As will be shown hereinafter, each of these unique combinations serves to identify the letter corresponding thereto, and can be reduced to voltage groups for controlling the reproduction of recorded letter-sounds or for any other desired purpose.

A further feature to be noted in connection with Figure l is that the black reflecting areas within each of the five zones are not all of the same length or duration. For example, in the case of the letter 1), the areas of black reflection occurring in the first and third zones Z1 and Z3, are all of short duration, while the areas of black reflection occurring in the second and fourth zones, Z2 and Z4, are of longer duration. This is shown by the difference between the lengths of the shaded portions of the lines L1-L4 occurring under the letter b in Figure 1. As will be shown hereinafter, distinctions between long and short black reflection areas, within each of the segmental zones Z1-Z5 defined by the paths of the light spots S1-S5 of Figure 1, can be relied on as an aid in identifying the various characters of printed matter.

In Figure 2 of the drawings, there is shown It will be understood that the a complete reading aid system arranged in ac cordance with the invention, with certain of the parts shown in perspective, and with the electrical circuit portions shown in block diagram form. In Figure 2, one of the elements of the reading aid system is seen to comprise a scanning device I0, for projecting light energy onto a sheet of printed matter I5, and for picking up the light reflected from each of a plurality of segmental zones of the printed matter I5.

In Figures 3, 4, and 5, the scanning device I0 of Figure 2 is shown in detail, and is seen to include (see Figure 3) a source of light energy, such as an incandescent lamp l1, placed above a perforated mask IZ which serves as the virtual source of a plurality of light beams I3. The light beams I3 are focused on a sheet of printed matter I5 by means of a focusing lens I6, and serve to form the light spots S1-S5 previously referred to in connection with Figure 1.

Figure 4 is a side view of a combined light projection and light pickup device, such as may be used in the scanner II! of Figure 2, and which may comprise a group of quartz or Lucite (methyl-methacrylate resin) light collectors l1, separated by light shields I8 to ensure absolute separation between the segmental zones of the printed matter. Each of the Lucite collectors I'I conducts reflected light to a light-sensitive element 20, such as a photoelectric cell or a photo-multiplier, wherein changes in the amount of reflected light are translated into changes in output current or voltage. The changes in the output voltage of the light sensitive elements 20 are utilized in the circuits of Figure 2 to distinguish between the characters of the printed matter.

Figure 9 shows the elements of a modified scanning arrangement suitable for use in the apparatus of Figure 2. In Figure 9, the indiciabearing surface comprises a photographic film IQ of comparable translucent medium having the indicia to be translated thereon. In this case, the light source II, the perforated mask I2, and the lens I6 are located on one side of the surface I4 having indicia thereon, while the light sensitive elements 20 and the light shields I8 are located on the other side of the surface I4. In this case, changes in the amount of light passing through the film are translated into changes in output current or voltage by the photocells 20. It will be observed that the scanning arrangement shown in Figure 9 differs from that shown in Figures 3, 4, and 5 only to the extent that variations in light-transmitting properties of the surface I4 having indicia thereon are utilized in the scanning arrangement of Figure 9, while variations in light-reflecting properties of the indicia-bearing surface are relied on in the scanning arrangement of Figures 3, 4, and 5. For simplicity, the present discussion will be limited to scanning a surface having indicia thereon of contrasting light-reflecting properties. However, the terms light-reflecting properties," and reflected light, as used herein and in the appended claims, will be understood to include light-transmission properties and transmitted light as explained in the foregoing.

As shown in Figure 2, the output of the scanner I0 is connected to a plurality of counting circuits 2|, wherein the number of white-to-black reflectance changes, occurring in the course of scanning each printed character, are counted. Pulse length detectin circuits 22 may also be used, to distinguish between;magic-reflecting; oigd fi rentilengthstwithin achzofl h hyp th icalszones. The-countersz l anagthe ul elength detectors 22:, Provide inicrmation: e. form: groups. otr voltages, eac tinctive ofapredet rminedi mber; trefiec a .lsuch srouni bein 1 i changes of predetermined: duration. Th *sIQilP said input conductors bein cconnectedginpredetermined. groups.- through high resistancae ments to. conductors: servingas;output con ctor for. thanetwork, 1 the arrangements .-v being; such that; notwo output z conductors aretconnected to the same groupcof. input ;,conductors.1 In such; a

network, individualivoltages applied toall ,of the input conductors. can, be: combined:- in .predetcr mined .groupsrforranyqdesired purnpsehasr for ex- -,ample,- the. separation of ;voltage groups characteristicofprintedcharactersa a In :the f nction-imatrix: 3, the var ous groups at vol age from the-circuits 2 I ZZrares I sate or--irecosn zedff-and m det vai able as con o v lta f raplur h y: i sele torm l e 2 he s l t rea pliflcrs 5 s ec vel ont olc h outputpfzaisoimdirr producing s st m The sound reproducing; system 26- may-comprise airotatable; magnetic; drum 2 1;, driven ,by a

' motor 28; and; provided :with alpluralit of a magnetically recorded soundtracks 1 29 spaced axially along; the surfaceiofh-the. drumll; Each ofthe soundtracks ez9'acom'prises a-v recordin of one. .of the letter; or other.- sounds characteristic.- of a I spoken language, and isso-mecorded that one complete-reproduction oIFtheJetter-sourid can be had in .one :retolutiomot the drum; 2.1 A signal pickup un-itlmagnetic sound-head) 31 is provided 1 foreach ..of thez -sound tracks: 29;. eachof. the pickup units 3| being connected-to an individual selector-amplifier circuit 25. The drum 21 is rotated continuouslybythemotor 28;. so that an electrical signal corresponding toone of the letter sounds recorded on the drum 2 l is continuously available at eachot the.- pickup units.3'|. 'When thetunction matrix 23 recognizes a-voltage group corresponding -toa particular-printed letter or-character one of the-selector amplifier circuits 25 will pass the signal generated bythe pickup --unit 1 31 associated therewith, and the se-. lected signal=will be converted into-acoustical f energy-by a loudspeaker 3 2 connected in parallel withall of -the-- selector amplifier circuits- 25.

In order-te-in'sure that the reproduction of each letter sound will beginat theproper point the rotation; of the drum= 21, an;-"additional signal track: 3615 pnovided onthe' drum 211' The signal "track 36= carries a recorded synchronizing pulse which picked up by a pickup unit 3.3 and. passed jintofareadaandereset generatorcircuit 34. In "the generator circuit 34, voltages are generated for'partially energizing .all oflthe selector amplifiers' 25 ,at .the end or? each ,letter scan,f andv .for rese ting" he: counti g. ci u ts-X 1, s wi l. b 7 fiescribed'hereinai-ter. itiwill be understoodthat" he part cu ar o m-oi oii d-j n oduci a syst milshe n is pu e y .ilmst'r t r t nd; c ld a W compris jpthfi f ompara lesy te akno ninth Q s it-.2.Fer:tram soe ir nmescieg sys emsl f the type described in the aforementioned Flory rare-a metrically' coupled toueach otherand to acOm- 6!- app cat n re t e Ior sen. e reedine id o thepre enttinven ion. V

inemow nsideration iotz pecificcirwi s orrespondin Qo hQ- k diag am p tion of Figure 2, in Figured there is.,shown a diagram ot a counter circuittll-and-a pulse length deteeter circuit ZZ corresponding; to the lettered blocksll; 22 int-the system of Figure 2. In order to simp fy;the-,-dra;wing only one counter circuit 2| and one pulse-length deteoting circuit .22 haye been shown in Figure-6, although it will be understood -that the total number of counting circuits 2! will correspond-i302the selected number-of segmental zones of illumination in any particular sys tem,: while thei nurnber of pulse -length .detectns.- ci itsmay: va y; d pend n 1 on yp face of the letters tOwbesQaIined, In-the-system presently; being; described, five; count ng-v circuits 2| and five pulse len th detecting;-;circuits;22,are

required! V The input stage for the countingcircuit; 2| comprises .one of, the phctocells 20 of the scanin vicezlfliof Figure 2, thea r ns ment eing such .thata positive pulse 1 of voltage will be developed at the;0utput 24 ofthe photocellztl when ;the;am0untgof jreflected light reaching the photocell decreases; This of course, will; occur when a b1acky portion'jof aprintedycharacter appears in the zone corresponding to that photocell. Each: positive. pulseiromthe; photocell 20 is inverted in an; amplifiertiz so that anegative pulse; will appearaatithe plate: of the. amplifier 35 duringithe-scanning ,of anyarea .of blackrefiection in'the zoneyassociatedtherewith. The

pulse counting -portion; ofthe circuit 2| comprises three,binarycounterstages 31, 38, 39, of a type well known inthe arts (See e..g. U. S. Patents 2,404,047: and 2;!110-,156)-. Each binary counter stage. 31, 38; 39:consistsof abalanced triggercircuit, comprising. a; pair ofxvacuum tubes symm'on source .of plate; supply voltage (not shown). A balanced trigger circuit-of this type will remain in astablecondition, with eitherone of the 'tubes conducting and with-the other-tube nonconducting, until a negative; triggering; pulse is applied to the-grid of the conducting tube, or until a positive triggering pulse is applied to the grid of the. nonconductingtube, to cause arevers-al of the circuit conditions. The circuit will then remain quiescent in the new-condition of conduction-nonconduction until a suitable pulse is applied to the grid ot one of the tubes, whereupon the circuit will return to its original condition.

In-the counting circuit 21 of Figure 6, positive triggering pulses from a reset circuit 34, (see Figure 8) to be described hereinafter, are utilized to make the tubes 31a, 38a, 39a the conducting tubes prior to any counting action in the circuit 2| i. e. to bring the circuit 2] to the zero-coun condition); A- negative pulse applied to the first stage 3Tof the counting circuit 21 from the amplifier 35 (when the-circuit 2i 'is in the zerocount condition) will cause the tube 31a tocut off, with the result that the other-tube 31bin the first stage-31 will beturned on. A-second stas s;; 3lr r 8 t siturn dpn;.thet su-lt n svoltage drop at the plate of that tube will generate a negative carry-over pulse which is applied to the next succeeding stage of the counter circuit 2|. Therefore, the first negative pulse occurring at the input to the counter circuit 2| will cause a reversal of conditions only in the first stage 31, the second negative pulse will cause a reversal in both the first and the second stages 31, 38, the third negative pulse will cause a reversal only in the first stage 31, and the fourth negative pulse will cause a reversal in all of the stages of the counter 2|.

The output of the counter circuit 2| is taken from leads C1, C2, C3 connected to the grids of the tubes 3'"), 38b, 39b, respectively in the counte circuit.

In order to simplify the discussion, the terms high and low voltage have been used herein to designate more positive and less positive voltages, respectively, rather than the relative absolute magnitudes of voltages. When the circuit 2| is in the zero count" condition, all of the output leads C1, C2, C3 will be at a relatively low potential corresponding to the cut-01f voltage on the grids of the tubes 31b, 38b, 3%. When a first negative pulse is applied to the counter circuit 2|, the voltage on the lead C1 from the first stage 2 will become relatively high as the tube 31a is cut on and the tube 31b is turned on. On the application of a second negative pulse to the circuit 2|, the voltage-on the lead C2 from the second stage 38 will become relatively high, while the voltage on the lead C1 from the first stage 31 will again become relatively low. The third applied negative pulse will cause the voltage on the lead C1, from the first stage 32', to become relatively high, but will not afiect the other output leads C2, C3, while the fourth applied negative pulse will cause the voltage on the leads C1, C2, from the first and second stages 31, 38, to become relatively low, and will cause the voltage on the lead C3 from the third stage 39 to become relatively high. Thus, a difierent group of high and low voltages will be available on the output leads C1, C2, C3 after every negative pulse (up to 4 in number) which is applied to the circuit 2|. This is shown in the following table, wherein the relative voltage on each of the output leads C1, C2, C3 is shown, for the zero-count condition, and after each of four negative pulses from the amplifier 35 have been applied to'the circuit 2| The voltages on the output leads C1, C2, C3 of all of the counter circuits 2i in the system of Figure 2 are carried into the function matrix 23, and will be referred to again in the discussion of Figure '7.

After any one character of the printed matter has been scanned, it is necessary to reset the counter circuit 2| to the zero count condition. This is accomplished by applying a positive reset voltage pulse to the grids of the tubes 31a, 38a, 39a in the counter circuit 2i, through a reset bus 4|. The reset pulses for the counter circuit 2| are obtained from a read-reset circuit 34 associated with the sound reproducing device 26 in Figure 2, as will be described hereinafter in con- 'nection with Figure 8.

As was previously mentioned, a pulse length detecting circuit 22 is used in the system of Figure 2 for distinguishing between black refiectance pulses of long and short duration. It will be understood that the distinction between long and short black reflectance pulses is only a relative concept, and that the actual duration of each black reflectance pulse will be dependent upon the rate at which the printed material is traversed by the scanning device [0 in Figure 2. However, for any substantially constant scanning rate, the duration of the long and short black reflectance pulses will also be substantially constant.

In Figure 6, there is shown a pulse length detecting circuit 22, which includes three trigger stages 42, 43, 44. Two of the trigger stages, 42 and 43, are of the unbalanced, or so-called slide-back type, described in U. S. Patent 2,404,047, while the third trigger stage 44 is of the balanced type previously described herein.

As is explained in U. S. Patent 2,404,047, an unbalanced or slide-back type of trigger circuit, such as the stages 42 and 43 of Figure 6, hasa normal, predetermined condition of conduction-nonconduction. For example, in the stages 42 and 43, it is assumed that the circuit constants have been so selected that the section 420 is the normally conducting section in the stage 42, while the section 43c is the normally conducting section in the stage 43. When a negative voltage pulse from the amplifier 35 is applied to the normally conducting section of either of the unbalanced trigger stages 42, 43, the conditions of conduction-nonconduction in that stage will be reversed, and will remain reversed during the time that the negative voltage pulse is applied thereto. When the negative pulse ends, circuits 42, 43 will return to their normal, predetermined condition after a time interval determined by the parameters of the circuits. The

parameters of the first unbalanced trigger stage 42 are so chosen that the stage 42 will return to its normal condition of conduction (i. e. with the tube 420 conducting) almost immediately at the end of any negative voltage pulse applied thereto. The parameters of the other unbalanced trigger stage 43 are so chosen that the stage 43 will remain reversed, after the end of an applied negative voltage pulse, for a time slightly shorter than the predetermined time required to scan a long black reflection area.

The first unbalanced trigger stage 42 is coupled directly to the amplifier 35, while the other unbalanced trigger stage 43 is coupled to the amplifier 35 through a differentiating circuit comprising a capacitor 46 and a resistor 41, and through a rectifier 48. Negative voltage pulses at the plate of the amplifier tube 35 will appear in substantially unmodified form at the grid of the normally conducting tube 420 in the first trigger stage 42, while a short duration (differentiated) negative pulse will appear at the grid of the normally conducting tube 430 in the second trigger stage 43 for each negative pulse, regardless of duration, at the plate of the tube 35. Hence, the first unbalanced trigger stage 42 will remain inverted for a time substantially equal to the duration of any negative pulse at the output of the amplifier 35, while the other unbalanced trigger stage 43 will always return to normal, after reversal, within a time interval slightly shorter than the duration of long black-reflectance pulses. The relative duration of each negative, blackreflectance pulse from" the amplifier 35 will determine which of the two unbalanced trigger stages 42, 43 will return" last to its normal condition of conduction, and in'view'of the foregoing discussion, it" will be apparent that the unbalanced trigger stage 43'will be the last to revert to normal after the occurrence of a short black-reflectance pulse, while the unbalanced trigger circuit 42 will be the last. to revert to normal after a long black-reflectance pulse.

The balanced trigger stage '44 of the pulselength detector 22 serves to reduce pulse-length information, derived from the two unbalanced trigger stages 42, 43, into useable form. As shown in Figure 6, each of the sections 44a,'44b of the ablanced trigger stage 44 is connected to the normally nonconducting (d) section of one of the unbalanced stages '42, 43. When either of the unbalanced stages 42, 43 returns, to normal after reversal, a positive pulse will be applied to the/corresponding section, 44a or 44b, of the balanced trigger stage 44, forcing conduction in that section. It follows,-then, that the conditions of conduction non-conduction in the balanced trigger stage 44, after the termination of each black-reflectance pulse, willbe indicativejof the relative duration of that black-reflectance pulse. The output of the pulse length detectingcircuit 22 is taken from the grid of the section 44a of the balanced trigger stage on a lead, and is in the form ofa relatively "high or low voltage,'similar to the output of each stageof the counting circuit 2 I. It will be seen that a high voltage on the lead 149 will indicatetheoccurrence ofa long -bladk+reflectance area in the zone with which a particular-pulselength circuit 22 is associated, while a low voltage on the lead 49 will indicate a short black-reflectance area. The leads 49 from all of the pulse counting circuits2-2 of Figure 2 are connected into the function matrix 1'23,\and willbe referred to again in-the discussion thereof In Figure 7, afunctio'n matrix'23 is shown, which comprises twenty horizontal? input leads C1, CzQCg, 49,;andtwenty-six vertical output leads 50, interconnected by high resistance elemerits sayiofthelorderof several'megohms. In'order to simplify "the drawing, the resistors 5| have been shown as'h'eavy dots at the intersections of 'the input and output leads interconnected'thereby. The inputleads CIT-C3, 49 of the function matrix 23 are arranged in five groups or channels, each suchchannel corresponding to one of the zones Z1Z5 of the printed matter to be scanned. It will be understood that the inputleads "C1, C2, C3, 49for each channel are-merely extensions of the output leads C1, C2, C3 of the pulse counting circuit 2| :of Figure 6, and of the output lead 49. of the-pulse length detecting circuit 22 of Figure .6. As was previously explained, five of each of the counting and-pulse lengthcircuits 2|, '22 are required-in the system presently-being described. Each of the'output leads50= of the function matrix 23isallotted to one of the "letters of an alphabet, and is connected to a preselected group of input leads -C1 Ca, 49, from the various channels. It should be noted 'thatfithe particular function matrix 23shownin Figure 7 is properly connected for'recognition of an alphabet set in the type-face shown in "Figure '7 only. This is necessary for the "reason that one letter, set ina giventype-face, may yield a differentcharacteristic pulse count in one or more 1 zones than the same letter will yield when set in a different type-face. Howeverpth'eprinciples tolaerapplied in connecting a function matrix to recognize any I given type-face "are. always the same, and merely rq'uire a I 'predetermination "of x the pulse counts which are peculiar to the particularletter and typ'e face "involved;- For example, -in the case of the letter b,' it will be seen: in Figures 1 and 1a that .the letter b'will yield-one'pulse in zone number l,'one (long) pulsevinz'onesi and 4, two pulsesin' zone number '3,"and zero pulses-inzonenumber 5. Referring tothe table above, it 'will be seen :"that the'foregoirig pulse count will result 'in" a: high voltage on the lead C1 in channels I ,"12, and "4; a high voltageron'the lead C2 in channel 3, 'a-lo'w voltageon the leads C1, C2,' a'nd Csin channel 5, and 'ahigh voltage on the pulse length Ie'ad 49= in channels 2. and=4 (due tothe occurrence of long black-refiectanc'e pulses in each-of the zones 2 and" 4). Thus, at the end lof sc'anning'the letter fbf allf input leads of the matrix 23 whichare connected-to the 11" output lead win he in the high wonage condition. On'the ether-hand, a computation of the pulse coum in'eachzonefor each of the other letters, fa, of the alphabet will show that, 'for any letter other than 21" one or moreof the input leads ofthe function matrix 23 to which the output'lea'd lill i'or thelet'ter b is connected, will be in theflow }volt age "don dition. A plurality of selector amplifier cirjcluits 25, of'the type =shownin FigureB,fare provided, to distinguish between'var'ious voltage con'ditions at the matrix output leads 5t; as will now b'e desoribed. f

Each of the; output leadsifl ofthefuntion matrix 23 is connected "to one of 'thesele'c tor amplifier circuits '25, three of which are shown in Figure 8. 'It will beunderstoodthatiafcom plete system as shown in Figure '2 "rqm'resat least twenty-six sema namp iner p1 hits 25. The selector a'mpli'ner "circuits "25f unctionffas gate circuits,'permittirig signais tqp'ass there: through only under certain predetermined con. ditions. Each of the"s:e1e:ct amplifiers 2'5",18 adapted toreceive "a signal, corresponding 'to the recorded letter-sound, rrom'a pickup 'coil 53 in one of' the pickup heads BI '01: Figure 2 The grids of all'of the selector "amplifiers 25 are connected throueh'a common lead 54 to one of the sections 55d'ofa trigger circuit 55. The triggerrcircuit 55 forms'p'art of aread-and-reset voltage generator circuit-3'4, and is of the unbalanced or slide-back type previously described, wherein the sectiontbd is the normally nonconducting section. The cut-ofi' voltage normally present'atfthe grid of the section 55d ,is applied to each of the'selectorampuner circuits 25 via the lead-54. 'l-lenca 'none of 'theselector amplifiers 25 can pass audio; frequency slgnals from thepickup coils 55 untilthe'grid bias Ifor a given'am'plifier'25 has been raised above the cut-off level. It has *alreadybeen s'hownt hat the scanning of any given letter in the printed matter leaves'a high voltage o'nall iiiput' le'ads of th'ematrix 23 which are common to the matrix output lead'fifl as'sociated with that letter, While this condition is one of tliemequirements for turning on any given amplifier 25,"it is also necessary that the voltage on'tlie lead 54 be raised by reversalof the trigger circuit fi before a given amplifier 25 "will pass 'an'y signals. is order 'toexpla'in the actionof -t he'read' and-r'st trigger circuit 55, it is necessary to refer back to the action of the counting circuit 2| of Figure 6. e

It will be recalled that a negative voltage pulse will appear at the plate of the amplifier 35 in the counting circuit 2| of Figure 6 whenever black reflecting conditions occur in the zone associated therewith, and will persist for the duration of the black reflectance. The plates of the amplifier tubes ,35 in the counting circuits 2| for all of the zones I through are connected to the grid of the input stage 56 of the reset circuit 34, througha lead59. As long as black reflectance persists in any zone of the printed matter, the voltage at the grid of the input stage 56 of the circuit 34 willremain below the necessary level for conduction therein. However, when the scanningof any one letter has been completed, the voltage at the plates of, all of the counting circuit amplifiers 35 will rise, permitting conductionin theinput stage 56 ofv the circuit 34 of Figure 8 A coil 51 in the grid circuit of the input stage 56 comprisesthe pickup coil in the synchronizing-pulse pickup unit33 in Figure 2. In Figure 8, when the input stage 56 is turned on at the end of a letter scan, a negative pulse from the coil 51 will cause a reversal of conditions in .the trigger circuit 55. The resulting rise in voltage on the lead 54 will complete the gating action in any selector-amplifier which is properly energized by a group of high voltages from the function matrix 23, and the selected letter-sound signal will be passed through the amplifier 25 and a common amplifier stage 60 to the loudspeaker 32 in Figure 2. The slide-back time of the trigger stage 55 of the circuit 26 is made equal to the'reproduction time of one recorded letter sound (i. e. one revolution of the drum 2'! of the sound reproducing system 26 in Figure 2). At the end of each'sound reproduction period, a' positive pulse will be generate'dat the plate of the nor mally nonconducting section 55d of the trigger circuit 55 as the latter reverts to normal conditions, and it is this positive 'pulse which is the reset pulse for the counter circuits 2! of Figure 6.

Summarizing, briefly, the action of the system of Figure 2, it has been shown that any given selector amplifier 25 can operate only at the end of a letter-scan, anclonly on the occurrence of a predetermined high voltage group on'the' input leads of the function matrix 23 of Figure 7.

It has also been shown that the counter circuits 2| and pulse length circuits 22 are adapted to reduce light-reflection changes into voltage groups'distinctive of the letters of printed matter scanned with a plurality of light beams. It

will be clear, therefore, that a reading aidsystem of the type described is adapted to reduce printed matter into articulate sounds characteristic of a spoken language through the'medium of distinctive groups of control voltages developed in the course of scanning printed matter with a plurality of light beams. It should be noted that the information furnished by the pulse length detecting circuits 22 of Figure 2 can be dispensed with by using a larger number of scanning zones in order to obtain more pulse count information in place of pulse length information. Therefore, it will be understood that the method of light-to-sound translation described herein is not limited to the use of a uniform scanning rate. Moreover, it is apparent that individual light beams are not requiredwhere means, such as the separator masks I8 of Figures 4 and 5, are

used to separate reflected light from the printed matter.

It is apparent that the principles of indicia recognition and translation set forth herein are by no means limited to use with an acoustic reproduction system. For example, characteristic voltages or voltage groups generated in accordance with the invention could be utilized to control the operation of a Braille character printer in order to translate the characters of ordinary printed matter into Braille system characters. The invention is also applicable to accounting and tabulating systems for recognizing printed or perforated. indicia on index cards. Where perforated cards are used, a scanning system comparable to that shown in Figure 9 may be found to be advantageous.

An alternative form of apparatus for practicing the method of the present invention is shown in the copending application of L. E. Flory and W. S. Pike, Serial No. 68,888, filed January 3, 1949.

It is also apparent that arbitrary coded indicia other than the characters of an alphabet could as well be recognized by the method and apparatus described, such as the punched or perforated patterns comprising Teletype code and the like.

Since many such modifications are possible in the method and apparatus shown and described, all Within the scope and spirit of the invention, the foregoing is to be construed as illustrative, and not in a limiting sense.

What is claimed is:

1. Apparatus for recognizing and translating from a given surface indicia thereon of contrasting energy-reflective properties, said apparatus comprising, a source of energy, means forscanning a plurality of segmental zones of said surface with beams of energy projected upon said surface from said source, means including an element responsive to reflected energy originating in said beams and reflected from said surface for determining the number of changes in the amount of energy reflected from said surface within each of the zones scanned by said beams, and means effectively coupled to said last-mentioned means for generating voltages having a predetermined relation to the number of said changes counted for each of said zones.

2. Apparatus for recognizing and translating from a given surface indicia thereon of contrasting energy-reflective properties, said apparatus comprising, a source of energy, means for scanning a plurality of segmental zones of said surface with beams of energy projected upon said surface from said source, means including an element responsive to reflected energy originating in said beams and reflected from said surface for determining the number and the duration of changes in the amount of energy reflected from said surface within each of the zones scanned by said beams, and means effectively coupled to said last-mentioned means for generating voltages having a predetermined relation to the number and the duration of said changes for each of said zones.

8. Apparatus for recognizing and translating from a given surface indicia thereon of contrasting light-reflective properties, said apparatus comprising, a source of light, means for scanning a plurality of segmental zones of said surface with beams of light projected upon said surface from said source, means including an element responsive to reflected light originating in said beams and reflected from said surface for determining the number of changes in the amount of light reflectedfrom saidsurface within each of the'zones scanned-by said beams, and; means effectively coupled to said last-mentioned means for generating voltages having a predetermined relation to the number of said changes counted for each of said zones.

4. Apparatus for translating printed matter composed of a given surface having characters printed thereon of contrasting;energy-reflective properties into articulate sounds characteristic of a spoken language,=said apparatus comprising, a source of energy, means for scanning a plurality of segmental zones of said printed matter'with beams of energy projected upon said printed matv ter from said source, means including an element responsive to reflected energy originating in said beams and reflected from said printed matter tor determining the number of changesin the amount of energy reflected from said printed matter "within each of the zones scanned by said beams, means coup-led to said first named means for generating voltages corresponding to distinctive combinations of said numbers of changes, means for producing soundscharacteristic of a spoken language, and means responsive to said voltages from said generating means for controlling said sound producing means.

5. Apparatus for translating printed matter composed of a given surface having characters printed thereon of contrasting light-reflective properties into articulate sounds characteristic of a spoken language, said apparatus comprising, a source of energy, means for scanning a plurality of segmental zones of said printed matter with beams of energy project-ed upon said printed matter from said source, means including an element responsive to reflected energy originatin in said beams and reflected from said printed matter for determining the number and the duration of changes in the amount of energy reflected from said printed matter within each of the zones scanned by said beams, means coupled to said first named means for generating groups of voltages corresponding to distinctive combinations of said numbers of changes, means for producing sounds characteristic of a spoken language, and means responsive to said voltage groups from said generating means for controlling said sound producing means.

6. Apparatus for translating printed matter composed of a given surface having characters printed thereon of contrasting light-reflective properties into articulate sounds characteristic of a spoken language, said apparatus comprising, a source of light, means for scanning said printed matter with light projected upon said printed matter from said source, means includin light pickup elements responsive to reflected light originating at said source and reflected from segmental zones of said printed matter for determining the number of changes in the light-reflective properties of said printed matter within each of said zones as said printed matter is scanned, means coup-led to said first-named means for generating groups of voltages having a predetermined relation to distinctive combinations of said numbers of changes, means for producing sounds characteristic of a spoken language, and means responsive to said voltage groups from said generating means for controlling the operation of said sound producing means.

'7. Apparatus for translating printed matter composed of a given surface having characters printed thereon of contrasting light-reflective properties into articulate' sounds characteristic of a spoken" language, said apparatus comprising, a

source of light, means forscanning a plurality of segmental zones of'said printed matter with a plurality of. light beams projected uponsaid printed matter from said source, means including a light sensitive elementjficrpicking upreflected light originating in said beams and reflected from said printed matter, a counting circuit coupled to said pickup means for counting the number of recordings for. producing sounds characteristic of a spoken language, and means adapted to distin-' guish between and to respond to said'voltage groupsfor controlling the operation ofsaidsound producingmeans.

f8, Apparatus for translating printed matter composed of a given surface having characters printed thereon of contrasting light-reflective properties into articulate sounds characteristic of a spoken language, said apparatus comprising, a source of light, means for scanning a plurality of segmental zones of said printed matter with a plurality of light beams projected upon said printed matter from said source, a plurality of light sensitive elements for picking up reflected light originating in said beams and reflected from said printed matter, a plurality of counting circuits and a plurality of pulse-length detecting circuits coupled to said pickup means for generating groups of voltages representative of the number and of the duration of changes in the amount of reflected light picked up by said elements from each of said zones as said printed matter is scanned, sound producing means including a plurality of reproducible recordings for producing sounds characteristic of a spoken language, and means adapted to distinguish between and to respond to said voltage groups for controlling the operation of said sound producing means.

9. Apparatus for translating printed matter composed of a given surface having characters printed thereon of contrasting light-reflective properties into articulate sounds characteristic of a spoken language, said apparatus comprising, a source of light, means for scanning a plurality of segmental zones of said printed matter with a plurality of light beams projected upon said printed matter from said source, a plurality of light sensitive elements for picking up reflected light originating in said beams and reflected from said printed matter, a plurality of counting circuits and a plurality of pulse-length detecting circuits coupled to said pickup means for generating groups of voltages representative of the number and of the duration of changes in the amount of reflected light picked up by said elements from each of said zones as said printed matter is scanned, sound producing means including a plurality of reproducible recordings for producing sounds characteristic of a spoken language, a function matrix connected to said circuits for separating said voltage groups, and means connected to said function matrix and responsive to said voltage groups for controlling the operation of said sound producing means.

10. Apparatus for translating printed matter composed of a given surface having characters printed thereon of contrasting light-reflective proper-ties into articulate sounds characteristic of gel-sass a spoken language, said apparatus comprising, a scanning device including (1) a source of light, (2) means for illuminating a plurality of segmental zones of said printed matter With a plurality of light beams projected upon said printed matter from said source, and (3) a plurality of light collectors and a plurality of light sensitive elements for picking up reflected light originating in said beams and reflected from said printed matter, means for converting changes in the amount of light picked up by said elements into voltage pulses, a pulse counting circuit and a pulse length detecting circuit coupled to said last mentioned means for generating groups of voltages representative of the number and of the length of pulses received by said circuits due to changes in the amount of reflected light picked up from said printed matter by said elements during scanning, a function matrix connected to said circuits for separating said voltage groups, sound producing means, and means for controlling said 16 sound producing means in response to voltage groups originating in said circuits and passing through said matrix.

VLADINLIR K. ZVJ'ORYKIN. LESLIE E. FLORY.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,602,469 Watson Oct. 12, 1949 1,751,584 Hausell Mar. 25, 1930 1,910,586 Bartholomew May 23, 1933 2,002,208 McFarlane May 21, 1935 2,198,248 Hansell Apr. 23, 1940 2,210,706 (Carlisle Aug. 6, 1940 2,228,782 Sharples Jan. 14, 19-11 2,380,667 Morrison July 31, 1945. 

